Lightweight Radiation Shielding Composites for Small Spacecraft

Radiation in space poses threats for both astronauts and electronic equipment.nbsp; While it is relatively easy to shield against non-ionizing RF and microwave radiation, shielding against higher energy ionizing radiation ndash; gamma rays, protons, neutrons and galactic cosmic radiation (GCR) ndash; is much more challenging.nbsp; With longer missions to Jupiter or future manned missions (higher cumulative radiation exposure for astronauts) and with the use of smaller spacecraft that cannot accommodate additional weight needed for shielding, the importance of lightweight radiation shielding to NASA has increased.nbsp; To be effective, conventional shielding materials typically need to be thick and material thickness increases the total unwanted mass to be carried by a small satellite, and the amount of power required to create a deflection field would require significant fuel, so again unwanted additional weight.NanoSonic proposes to continue to refine our lightweight composites consisting of multiple layers of graded atomic number (Z-number) materials as effective ionizing radiation shields beyond Low Earth Orbit (LEO).nbsp; Radiation attenuation as a function of areal density was researched during Phase I and NanoSonicrsquo;s material was 71% higher attenuation vs. polyethylene.nbsp; The shielding composites possess a tough woven Kevlar and Boron Nitride (BN) wound composite which could be used as the structural shells and support members of small satellites so serve multiple purposes (shielding, micrometeoroid impact protection, and structural support).nbsp; Preliminary research results with NanoSonicrsquo;s materials in the Department of Environmental and Radiological Health Sciences at Colorado State University (CSU), and at the NASA Space Radiation Laboratory (NSRL/BNL), have shown that our materials significantly attenuate X-rays and gamma rays without secondary radiation, and structurally survive simulated 50-year exposure to solar energetic particles (SEP) and GCR.nbsp;